libstrat: fix compilation without pre-compiled header/without lto

libraries/libstratosphere/source/ncm/ncm_install_task_base.cpp

@@ -648,7 +648,7 @@ namespace ams::ncm {
 
                 /* Automatically choose a suitable storage id. */
                 auto reader = content_meta.GetReader();
-                StorageId storage_id;
+                StorageId storage_id = StorageId::None;
                 if (reader.GetStorageId() != StorageId::None) {
                     storage_id = reader.GetStorageId();
                 } else {